This invention relates to an aqueous polymer emulsion latex composed of particles comprising a vinyl polymer and a surfactant containing hydrophobic and hydrophilic moieties wherein said latex contains silicon moieties and amido functionalities and to processes for preparing the same. This invention additionally relates to coating compositions containing such aqueous polymer emulsions, to processes for coating a substrate and to the coated product resulting therefrom. The aqueous polymer emulsion latex when applied as a coating on a substrate and cured at ambient or elevated temperature, has been found to have excellent solvent, chemical and water resistance, exterior durability, impact resistance, abrasion resistance, excellent adhesion to a variety of substrates etc.
In general, materials that can be used as our surfactants are not new. The prior art discloses the preparation and use of water-based organic compounds having both silane and ionic functionality. Thus, Chang in U.S. Pat. No. 3,941,733 discloses the preparation of a water-based poly(urethaneurea), terminated by hydrolyzable or hydrolyzed silyl groups and carrying solubilizing moieties, useful for coating leather. Similarly, Gaa et al in U.S. Pat. No. 4,582,873 prepare water-based poly(urethane) urea polymers carrying pendant siliconate anions and solubilizing moieties for use as coating materials. Tominaga in EP 0276469 uses ionic functional polyacrylate and polyepoxide resins carrying silane functional groups as water-based electrodeposition coating compositions.
The synthesis of latexes in the presence of a surfactant not containing a silicon moiety is not new. For example, the prior art also discloses the polymerization of ethylenically unsaturated monomers in the presence of ionic-functional water based polymers to produce latexes. Thus, Ranka et al in U.S. Pat. No. 4,647,612 disclose the use of an acid salt group containing polyurethane in the polymerization of a polymerizable alpha, beta-ethylenically unsaturated monomer. In U.S. Pat. No. 4,318,833 Guagliardo polymerizes an ethylenically unsaturated monomer in the presence of a water-soluble polyurethane composition formed by the reaction of a diisocyanate compound with a polyol and a compound containing an acid sat group. In U.S. Pat. No. 4,644,030 Loewrigkeit et al also polymerize an ethylenically unsaturated monomer in the presence of a polyurethane carrying a pendant carboxylic group, in salt form, for use as a coating composition. In none of these references, however, does the ionic-functional water based polymer contain silicon.
It is also known in the prior art that latexes containing silicon can be prepared with silicon free surfactants, and that these latexes can be mixed with water soluble silicon containing resins. For example, Takayuki Kamiie et al disclose in Japanese Patent No. SHO 61 [1986]-47178 an aqueous coating composition for coating an inorganic building material which consists of (A) a water-soluble or water-dispersible acrylic copolymer containing alkoxysilane and carboxyl groups and (B) colloidal silica. In Japanese Patent No. SHO 61 [1986-155474 Takayuki Kamiie et al disclose a coating composite containing (A) a water soluble or water dispersible acrylic copolymer containing alkoxysilane and carboxyl groups and (B) an aqueous resin dispersion prepared by emulsion copolymerization in an aqueous medium (1) an alpha,beta-ethylenically unsaturated monomer, (2) a monomer containing a polymerizable unsaturated double bond and an alkoxysilane group and (3) colloidal silica. These Japanese systems, therefore, are made up of two separate and distinct entities. This is obviously true of the above Japanese Patent No. 47178. As to the above Japanese Patent No. 155,474, the one entity is comprised of a water soluble or water dispersible acrylic polymer containing alkoxysilane and carboxyl groups, while the other entity contains a vinyl resin carrying a silicon moiety, a surfactant devoid of silicon and colloidal silica. Kawakami et al in Japanese Kokai Tokkyo Koho JP 02,178,301 disclose the emulsion polymerization of ethylenically unsaturated silyl-reactive monomers in the presence of an acrylic water-soluble silyl containing acrylate resin. The present invention, however, involves the use of surfactants containing hydrophobic and hydrophilic moieties, silicon moieties and amido functionalities for the preparation of novel aqueous polymer emulsion latexes composed of particles comprising a vinyl polymer and a surfactant containing hydrophobic and hydrophilic moieties wherein said latexes contain silicon moieties and amido functionalities.